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United States Patent | 5,247,379 |
Andersson ,   et al. | September 21, 1993 |
An electro-optical device including a chiral nematic liquid crystal disposed between flat plates treated to weakly enforce molecular orientation along one preferred direction parallel to the plates. The plates are spaced by a distance small compared to the pitch of the helix typical in a bulk of the material, or the helix compensated by additives to ensure the equivalent situation. By an externally applied electric field the liquid crystal molecular orientation is rotated in a plane parallel to the plates away from the preferred orientation an angle the sign and size of which depends on the sign and magnitude of the field. The optical axis of the liquid crystal, oriented along the molecular orientation, is thus controlled by the external electric field in such a way as to make a linear light valve or other electro-optical device.
Inventors: | Andersson; Gunnar (Goteborg, SE); Komitov; Lachezar (Goteborg, SE); Lagerwall; Sven T. (Goteborg, SE); Stebler; Bengt (Goteborg, SE); Flatischler; Kurt (Bor.ang.s, SE) |
Assignee: | S. T. Lagerwall S.A.R.L. (Bandol, FR) |
Appl. No.: | 885285 |
Filed: | May 18, 1992 |
PCT Filed: | February 15, 1990 |
PCT NO: | PCT/SE90/00101 |
371 Date: | December 12, 1990 |
102(e) Date: | December 12, 1990 |
PCT PUB.NO.: | WO90/09613 |
PCT PUB. Date: | August 23, 1990 |
Feb 16, 1989[SE] | 8900562 | |
Mar 06, 1989[SE] | 8900777 |
Current U.S. Class: | 349/168; 349/124; 349/127; 349/132; 349/178; 349/179 |
Intern'l Class: | G02F 001/133 |
Field of Search: | 350/346,347 E,340,341,350 S,347 R 359/75,76,78,84,90,91,99,101,102,77 |
4469408 | Sep., 1984 | Kruger et al. | 359/75. |
4577930 | Mar., 1986 | Yang | 359/76. |
4838663 | Jun., 1989 | Lagerwall et al. | 350/341. |
4882207 | Nov., 1989 | Coates et al. | 350/341. |
4892392 | Jan., 1990 | Broer | 350/341. |
4917475 | Apr., 1990 | Meyer et al. | 350/346. |
4927244 | May., 1990 | Bahr et al. | 350/347. |
5116527 | May., 1992 | Coates et al. | 359/76. |
Foreign Patent Documents | |||
0219479 | Apr., 1987 | EP | 350/350. |
3711360 | Oct., 1988 | DE. |
"Linear Electroclinic Effect in a Chiral Nematic Liquid Crystal", Physical Review Letters, vol. 62, No. 7, Feb. 1989 (New York) Zili Li et al. pp. 796-799. Madhusudana et al.-"Linear Flexo-Electro-Optic Effect in a Hybrid Aligned Nematic Liquid Crystal Cell" J. Physique Letter 46(1985)-pp. L195-L200. Geary--"A Multiplexed Ferroelectric LCD Using AC Field Stabilized States", SID Digest--1985--pp. 128-130. Fergason--"Performance of A Matrix Display Using Surface Mode" IEEE Biennial Display Research Conference--1980--pp. 177-179. Garoff et al. "Electroclinic Effect at the A-C Phase Change in a Chiral Smectic Liquid Crystal" Physical Review Letters--vol. 38--No. 15--1977--pp. 848-851. |